Horizontal gene transfer in Archaea (Introduction)

by David Turell , Thursday, November 17, 2022, 15:02 (737 days ago) @ David Turell

As the oldest branch of life, this new finding is no surprise:

https://www.the-scientist.com/news-opinion/archaea-sport-structures-that-shuttle-genes-...

"Studies show that members of different domains can traffic genes back and forth, potentially fast-tracking evolution. How they do so remains unknown, but a study published today (November 16) in Science Advances provides a possible clue with the first report that archaea have integrons—gene exchange machinery previously thought only to exist in bacteria. This may allow microbes from the two domains to swap information and instantly acquire new functions. (my bold)

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"It was unknown if archaea have integrons, partly because they’re hard to study, says Ghaly, as they live in a variety of difficult-to-access environments, from our guts to muddy, sulfuric hot springs. But recent advances in genomic sequencing, in particular a technique called metagenome-assembled genomes (MAG), have allowed researchers to piece together archaea genomes from environmental samples.

***

"Bacteria swap genes in the form of a gene cassette that consists of a single gene and a gene recombination site called AttC. When they encounter stressful circumstances, bacteria exchange these cassettes like mixtapes, plugging them into and taking them out of their genomes.

"To begin the DNA transfer process, bacteria use integron integrase (IntI), a protein in the tyrosine kinase family. Intl induces recombination between the gene cassette’s AttC site and a region on the bacterium’s genome called an integron attachment site, or AttI. Bacteria end up with a long string of gene cassettes, strung together by AttC sites, in their genomes.

"On the bacterial genome, integrons consist of a gene for an IntI protein, Int, followed by a series of integrated gene cassettes. In the new study, the researchers screened all publicly available genomes of archaea, 95 percent of which were MAGs. They searched for AttC-like sequences and for sequences coding for IntI-like proteins. The researchers say they haven’t found a way to predict AttI sequences, and thus didn’t look for them.

"In the nearly 6,700 archeal genomes they scanned, the researchers found 75, spanning nine phyla, that had evidence of integrons. All of the archaeal integrons had the same structure and components as bacterial integrons. (my bold)

Comment: it is widely accepted Archaea were the first life, so it is no surprise transferring integrons were there. Note my bolds. They are a way to fast-track evolution. It is a tool for a designing God to use.